High Current Density Cation-exchanged SnO2-CdSe/ZnSe and SnO2-CdSe/SnSe Quantum-dot Photoelectrochemical Cells

Rajaram S Mane, Mu Naushad, M R Khan, Sambhaji Shivajirao Bhande, Shoyeb Shaikh, Pritamkumar Shinde, Sulaiman Mohammed Alfadul

Index: 10.1039/C8NJ01409D

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Abstract

Research on a combination of low and high-bandgap energy materials through an ion-mediated chemical transformation of the nanostructure of one material into another, especially, metal chalcogenide quantum dot (QD) solar cells plays a very important role in fast charge transformation process followed high power conversion efficiencies (PCE) by eventing surface charge recombination. Based on a coordination chemistry approach, present work demonstrates an importance of cation-exchange process in developing a bandgap engineering of over tin oxide-cadmium selenide (SnO2-CdSe) with zinc-selenide (ZnSe) and tin selenide (SnSe) as SnO2-CdSe/ZnSe and SnO2-CdSe/SnSe electrodes. Experimental conditions were optimized, initially, form optical and photovoltaic performances. Our best performing cation-exchange interface modified photoelectrochemical devices i.e. SnO2-CdSe/ZnSe, and SnO2-CdSe/SnSe have approved respectively 21% and 28% PEC improvements i.e. 3.78% and 4.41% with increadible curent densities of 19.82 and 28.40 mA/cm2 over SnO2-CdSe (1.63% and 9.74 mA/cm2), which is attributed to; a) the fast transfer of photo-generated electrons from the CdSe QDs sensitizer to SnO2 photoanode by virtue of synergistically favourable band gap engineering, and b) mitigation of reverse photogenerated electrons flow in presence of high band gap buffer ZnSe/SnSe layer which, otherwise, causes excessive recombinations. A simple cation-exchange interface modification process can, in general, paved the way for improving the performance of QD-based solar cells.